Team tips etc

[Kaboom]

Hi guys, I am from Admiral server .
I have a level 50 character names " Kaboom ".

I would like to mention that this is absolutely a fantastic game !! And I am totally addicted !

Now , I would like your help. The thing is... That I have been trying to gather more heroes and building them all..rather than concentrating on a few.

As a result, now I am not being able to cope up well in the Arena.

I have the following with me :-

Lvl 50 | blue +2 | 3 star | death knight
Lvl 50 | blue +2 | 3 star | Succubus
Lvl 50 | blue +2 | 3 star | Wind master
Lvl 50 | blue +2 | 3 star | Brute
Lvl 49 | blue +2 | 3 star | Lightening elemental
Lvl 50 | blue +2 | 3 star | Professional killer
Lvl 49 | blue +2 | 3 star | Bear warrior
Lvl 48 | blue +2 | 3 star | Cleric
Lvl 48 | Blue +2 | 2 star | Silencer
Lvl 50 | Blue +2 | 2 star | Commando
Lvl 48 | Blue +2 | 2 star | Shadow shaman
Lvl 48 | blue +2 | almost 3 star | War chief
Lvl 48 | blue +2 | 2 star | Ice mage

Please help me by suggesting on what should be the best line up for me and what skills should I concentrate on... As in skill 1/2/3.

P. S

There are several others I have like Necromancer, imperial executioner, machinist, shallows keeper, psychic sword, old curse, psychopath etc which I have not used at all.

Thanks
Kaboom